The invention relates to components, in particular hubcaps, for aircraft wheels. It also relates to an aircraft wheel assembly and, in particular, to one in which the assembly incorporates an axle housing sensing means, typically one or more components of a tire pressure sensing means such as a tire pressure indicating system (TPIS). Typically, such a wheel would be a nose wheel. In the case of a main wheel assembly where an antiskid brake control is present, wheel speed sensing means, usually a wheel speed transducer (WST) may also be incorporated.
Two major areas of concern to the aircraft industry are aircraft weight and noise. Reducing aircraft weight gives benefits in performance and cost of operation. This is especially true in the case of wheel and brake components that are only used during ground based maneuvers, such as during the take-off and landing cycles, but are carried with the aircraft throughout the flight. Such wheel and brake components have to be lifted into a storage bay during flight.
Aircraft noise is an area of increasing concern as the pressure for more flights out of busy airports in close proximity to residential housing increases. A significant source of aircraft noise during aircraft landing is created by the flow of air over undercarriage components when the landing gear is lowered from the storage bay when the aircraft is at low altitude during final approach to the runway.
All components of the landing gear, including the wheels, can contribute to the generation of noise when exposed to the air stream during landing so any reduction in the noise generation by any component will contribute to a quieter aircraft.
Attempts have been made to reduce noise from aircraft wheels during landing by using shields to smooth airflow over the wheel, however, such shields can reduce the flow of air required for cooling brakes, leading to thermal management problems and longer turn around times for aircraft. Where the axle protrudes beyond the wheel rim position it is found that the axle end and any fixing mechanism on the axle are a major source of the wheel noise and are not affected by such shields. Nose wheels are typically configured with an axle extending beyond the wheel rim.
Aircraft wheel and brake assemblies are typically mounted on a hollow axle, within which are mounted at least in part other components such as, for example, wheel speed transducers (WSTs) and/or one or more components of the tire pressure indicating system (TPIS). To prevent the ingress of dirt and moisture to mechanical and electronic components around and within the axle it is common practice to fit a cover known as a “hubcap” over the end of the axle.